Relativistic Particle Acceleration in a Developing Turbulence
Diagnostics and constraints for relativistic electron and ion acceleration in solar flares
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Transcript of Diagnostics and constraints for relativistic electron and ion acceleration in solar flares
Diagnostics and constraints for relativistic electron and ion acceleration in solar flares
N. Vilmer
LESIA –Observatoire de Paris
Ascona_June 7-11 2005
X/ -ray spectrum
RHESSI Energy range
Pion decay radiation(ions > 100 MeV/nuc)sometimes with neutrons
Ultrarelativistic ElectronBremsstrahlung
Thermal components
Electronbremsstrahlung
-ray lines (ions > 3 MeV/nuc)
T= 2 10 7 KT= 4 10 7 K
SMM/GRSPhebus/GranatObservationsGAMMA1GROGONG
-ray and neutron event on 03/06/82
(from Chupp et al, 1987): -Time extended neutron production at the Sun (~ 600s)-First GeV protons accelerated in t <16s at the beginning of the flare-Neutron Emissivity at the Sun: 7.4 1031 E–2.4 Neutrons/MeV/sr for 100<E<2000 MeV- Spectral slope in agreement with the one deduced from neutron decay proton measurements
-ray and neutron event on 24/05/90
• 24 May solar flare: GOES X9.3, N36 W76• One of the largest neutron event:
N>100 MeV= 3.5 1030 n sr-1
• Impulsive phase 75 MeV (2nd peak)• Extended phase, duration > 8 minutes:• High-energy -rays 100 MeV• Pion-decay radiation from 2nd peak of the
impulsive phase
-ray and neutron event on 24/05/90
From Talon et al., 1993
Debrunner et al 1997 PHEBUS/GRANAT observations
High Energy -rays
Solar neutrons
Spectral evolution of high-energy -rays
Deduced solar neutron production time profile(i.e. pion time profile)
NM CLIMAX observations of solar neutrons and prediction for a time extended neutron production
Background subtracted count spectraFrom PHEBUS/GRANATFull line: one of the best fits with electron and pion contributionsDotted line: electron contribution
Background subtracted count spectrumFrom 300 keV to 100 MeVFull line: one of the best fits with one electron bremsstrahlung component& pion contributionDotted line: electron componentElectron bremsstrahlung component:Ae= 1 10 5 = 2 Eroll= 40 MeVProton component:=2 Ntot= 8 1031 Emax= 750 MeV
-ray lines
Vilmer et al, 2003
• Proton spectra and numbers from pion decay radiation and -ray line radiation and neutron observations?
• Do we have a single energetic ion population from a few MeV/nuc to a few GeV/nuc
• Ion spectrum with =2 from a few Mev to Emax : no compatibility
• Ion spectrum with =3 from a few Mev to Emax : only with Emax = 750 MeV BUT GeV neutron production!!
• Ion spectrum with =4 from a few Mev to Emax : OK if Emax > 2 GeV for spectra 1 to 3 BUT not enough pion production for spectrum 4!!
• No single shape of energetic ions from MeV to GeV• Evidence of spectral breaks? Other forms of accelerated
energetic spectra?• Also found for other events (e.g. Kocharov)• (see some of the simulations of particle acceleration by Dauphin
et al)
X/ -ray spectrum
RHESSI Energy range
Pion decay radiation(ions > 100 MeV/nuc)sometimes with neutrons
Ultrarelativistic ElectronBremsstrahlung
Thermal components
Electronbremsstrahlung
-ray lines (ions > 3 MeV/nuc)
T= 2 10 7 KT= 4 10 7 K
Phebus/Granatobservations
Bremsstrahlung and Synchrotron Emitting Electrons (I)
• Simple relationship between the spectral indexes of cm-mm and HXR/GR producing electrons
• Spectral index from X-ray obs
Thick target production from electrons• Electron flux: F(E,t) x from X-ray obs• Simple relationship between electron flux in the X-ray source and instantaneous
number of electrons in the gyrosynchrotron emitting source (r)
F(E,t) ~ N(E,t)/T(E) with T(E) escape time
r ~ x = + 1
• Gyrosynchrotron
Note also: obs ~ L2 B
Higher frequencies from higher energy electrons
1.22 0.9r
Bremsstrahlung and Synchrotron Emitting Electrons (II)
• Mm-wave emission (86 GHz) produced by high energy electrons (1 MeV) with a flatter spectrum than 100 keV X-ray spectrum (e.g. Kundu et al, 1994, White, 1999)
• Early in the flare: production of relativistic electrons on short time scales
• 2 components of electron populations or result of acceleration process?
Electron-Dominated Events• First observed with SMM
(Rieger et al, 1993)
• Short duration (s to 10 s) high energy (> 10 MeV) bremsstrahlung emission
• No detectable GRL flux• Photon spectrum > 1
MeV (X-1.5—2.0)
• For 2 PHEBUS events o if Wi>1MeV/nuc We>20 keV
o No detectable GRL above continuum
o Weak GRL flares?
Vilmer et al (1999)
PHEBUS
BATSE
Bremsstrahlung and Synchrotron Emitting Electrons (III): Electron « broken » energy spectra
• Many evidence from HXR/GR observations that hardening of electron spectra above a few hundred keV (i.e. electron dominated disk event but also GRL events)
• Evolution of the break energy in the course
of the event
• Relation between mm/cm emitting electrons and electrons above Eb
PHEBUS& BernTrottet et al (1998)
Trottet, Vilmer et al. 1998
Bern and PHEBUS/GRANATobservations
= radio spectral index
Peak c- from HXR/GR = 4.1 for E<Eb = 1.5 for E>Eb-observed = 1.5
Peak d- from HXR/GR = 2.7 for E<Eb = 1.2 for E>Eb-observed = 1.3
Trottet, Vilmer et al. 1998
Bremsstrahlung and Synchrotron Emitting Electrons (IV):
Production of submm emissions by ultrarelativistic electrons?
First detection at 212 GHzNow also at 405 GHZ
(Kaufman et al, 2002,2004)
From Trottet, Raulin, Kaufman et al, 2002
Gyrosynchrotron emissionFrom power law energy distribution with = 2.7Corresponding to a mid size electron-dominated
event above > 100 kev(no observations)
Bremsstrahlung and Synchrotron Emitting Electrons (V):
Production of submm emissions by ultrarelativistic electrons?
spectre
Radio emitting electron spectra harder than the X-ray observed oneConsistent with = 2.3 in II and = 3.5 in III and B=500G
But electrons of energies around 10 MeV neededBreaks?
(from Lüthi et al, 2004)To be further investigated with flares also observed above a few MeV
II
III
Rise?
Analyse spectrale X/centimétrique
<<αα> = -1.2 (centimétrique) > = -1.2 (centimétrique) δδ = -2.7 (électrons) = -2.7 (électrons)
=1.22-0.9=1.22-0.9 (Dulk et March, 1982) (Dulk et March, 1982)
09:49:10-09:50:00
09:57:00-09:57:30
09:58:10-09:58:4009:57:40-09:58:0009:58:40-09:59:50
<α>2eme phase = -1.2
3 November 2003 event
From Dauphin et al, 2005
Hypothèse: électrons rayonnent dans les X en cible épaisse (Brown, 1971) Hypothèse: électrons rayonnent dans les X en cible épaisse (Brown, 1971) + propagation libre entre sources X et centimétrique: + propagation libre entre sources X et centimétrique: γγ==δδ+1(photons)= -1.7+1(photons)= -1.7
Flux total observé
Flux du bruit de fond
Fit reproduisant le mieux le flux total – le flux du bruit de fond
-1.6
raie du bruit de fond
Analyse spectrale de RHESSI Analyse spectrale de RHESSI Indice spectral des photons = -1.6Indice spectral des photons = -1.6
Population d’électrons énergétique Population d’électrons énergétique émettant le rayonnement X > 500 émettant le rayonnement X > 500 keV compatible avec le keV compatible avec le rayonnement centimétriquerayonnement centimétrique
Rear detectors (2 and 7 excluded) no pulse pile up correction Binning code 12
1 keV 3 to 60 keV2 keV to 120 keV5 keV to 250 keV
10 keV to 2250 keV50 keV 2250 keV to 7200 keV200 keV 7.2 MeV to 17 MeV
+ special binning around 511 keV and 2.2 MeV line
2003/11/03 09:58:49.999 2003/11/03
10:01:29.999 4.00969 3.26291 581.398 1.61146
1.4129 0
November 4, 2003 flare spectra
OVSA
Itapetinga
SST
Kaufmann et al, 2004)
A new component Starting from 200 GHz?
In relationship withHigh frequency radiations
U T (hh:m m ) 04/11/2003
0
50
100
150
200 0
5
10
15
200
1
2
150-500 keV
0.5-1.3 MeV
1.3-4 MeV
0.0
0.2
0.4
SO
NG
(C
OR
ON
AS
-F)
X-r
ay
an
d g
am
ma
-ra
y e
mis
sio
n,
ph
oto
ns/
(cm
**2
s
Me
V)
4-7 MeV
0.00
0.01
0.02
7-15 MeV
0.000
0.002
0.004
26-40 MeV
0.000
0.005
0.010
0.015
60-100 MeV
0.000
0.001
0.002
100-200 MeV
19:30 19:36 19:42 19:48 19:54 20:00
Observations Of high energy radiationBy SONG/CORONASMyagkova et al, 2004
2003 October 28
Trottet et al. 2005 in prep.
Koronas
Also for the 28 October flare
See Trottet et al